On Fri, 07 Sep 2001 01:34:46 -0400, Tom Lane wrote:

>there is still an unpatched reference to pg_description in
>getColumns(), in both jdbc1 and jdbc2.

This was introduced by Jeroen's patch (see
http://fts.postgresql.org/db/mw/msg.html?mid=1032468). Attached
is a patch that returns getColumns() to using "select
obj_description()" instead of direct access to pg_description,
as per the request by Tom.

I've incorporated Jeroen's fix to left outer join with
pg_attrdef instead of inner join, so getColumns() also returns
columns without a default value.

I have, however, not included Jeroen's attempt to combine
multiple queries into one huge multi-join query for better
performance, because:
1) I don't know how to do that using obj_description() instead
of direct access to pg_description
2) I don't think a performance improvement (if any) in this
method is very important

Because of the outer join, getColumns() will only work with a
backend >= 7.1. Since the conditional coding for 7.1/7.2 and
jdbc1/jdbc2 is already giving me headaches I didn't pursue a
pre-7.1 solution.

Regards,
Ren? Pijlman <rene@lab.applinet.nl>

Author: bmomjian

src/interfaces/jdbc/org/postgresql/jdbc1/DatabaseMetaData.java

@@ -13,7 +13,7 @@
 /**
  * This class provides information about the database as a whole.
  *
- * $Id: DatabaseMetaData.java,v 1.31 2001/09/06 12:53:15 momjian Exp $
+ * $Id: DatabaseMetaData.java,v 1.32 2001/09/10 14:55:08 momjian Exp $
  *
  * <p>Many of the methods here return lists of information in ResultSets.  You
  * can use the normal ResultSet methods such as getString and getInt to
@@ -1895,19 +1895,21 @@ public java.sql.ResultSet getTableTypes() throws SQLException
    */
   public java.sql.ResultSet getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern) throws SQLException
   {
+    // the field descriptors for the new ResultSet
+    Field f[] = new Field[18];
+    java.sql.ResultSet r;	// ResultSet for the SQL query that we need to do
     Vector v = new Vector();		// The new ResultSet tuple stuff
-	Field f[] = new Field[18];		// The field descriptors for the new ResultSet
-
-    f[ 0] = new Field(connection, "TABLE_CAT", iVarcharOid, 32);
-    f[ 1] = new Field(connection, "TABLE_SCHEM", iVarcharOid, 32);
-    f[ 2] = new Field(connection, "TABLE_NAME", iVarcharOid, 32);
-    f[ 3] = new Field(connection, "COLUMN_NAME", iVarcharOid, 32);
-    f[ 4] = new Field(connection, "DATA_TYPE", iInt2Oid, 2);
-    f[ 5] = new Field(connection, "TYPE_NAME", iVarcharOid, 32);
-    f[ 6] = new Field(connection, "COLUMN_SIZE", iInt4Oid, 4);
-    f[ 7] = new Field(connection, "BUFFER_LENGTH", iVarcharOid, 32);
-    f[ 8] = new Field(connection, "DECIMAL_DIGITS", iInt4Oid, 4);
-    f[ 9] = new Field(connection, "NUM_PREC_RADIX", iInt4Oid, 4);
+
+    f[0] = new Field(connection, "TABLE_CAT", iVarcharOid, 32);
+    f[1] = new Field(connection, "TABLE_SCHEM", iVarcharOid, 32);
+    f[2] = new Field(connection, "TABLE_NAME", iVarcharOid, 32);
+    f[3] = new Field(connection, "COLUMN_NAME", iVarcharOid, 32);
+    f[4] = new Field(connection, "DATA_TYPE", iInt2Oid, 2);
+    f[5] = new Field(connection, "TYPE_NAME", iVarcharOid, 32);
+    f[6] = new Field(connection, "COLUMN_SIZE", iInt4Oid, 4);
+    f[7] = new Field(connection, "BUFFER_LENGTH", iVarcharOid, 32);
+    f[8] = new Field(connection, "DECIMAL_DIGITS", iInt4Oid, 4);
+    f[9] = new Field(connection, "NUM_PREC_RADIX", iInt4Oid, 4);
     f[10] = new Field(connection, "NULLABLE", iInt4Oid, 4);
     f[11] = new Field(connection, "REMARKS", iVarcharOid, 32);
     f[12] = new Field(connection, "COLUMN_DEF", iVarcharOid, 32);
@@ -1917,105 +1919,93 @@ public java.sql.ResultSet getColumns(String catalog, String schemaPattern, Strin
     f[16] = new Field(connection, "ORDINAL_POSITION", iInt4Oid,4);
     f[17] = new Field(connection, "IS_NULLABLE", iVarcharOid, 32);
 
-	StringBuffer sql = new StringBuffer(512);
-
-	sql.append("select " +
-		(connection.haveMinimumServerVersion("7.2") ? "a.attrelid, " : "a.oid, ") +
-		"    c.relname, " +
-		"    a.attname, " +
-		"    a.atttypid, " +
-		"    a.attnum, " +
-		"    a.attnotnull, " +
-		"    a.attlen, " +
-		"    a.atttypmod, " +
-		"    d.adsrc, " +
-		"    t.typname, " +
-		"    e.description " +
-		"from" +
-		"    (" +
-		"        (pg_class c inner join pg_attribute a on" +
-		"            (" +
-		"                a.attrelid=c.oid");
-
-	if ((tableNamePattern != null) && ! tableNamePattern.equals("%")) {
-		sql.append("                and c.relname like \'" + tableNamePattern + "\'");
-	}
+    // Added by Stefan Andreasen <stefan@linux.kapow.dk>
+    // If the pattern are  null then set them to %
+    if (tableNamePattern == null) tableNamePattern="%";
+    if (columnNamePattern == null) columnNamePattern="%";
 
-	if ((columnNamePattern != null) && ! columnNamePattern.equals("%")) {
-		sql.append("                and a.attname like \'" + columnNamePattern + "\'");
-	}
+    // Now form the query
+	String query =
+	    "select " +
+		(connection.haveMinimumServerVersion("7.2") ? "a.attrelid" : "a.oid") +
+		",c.relname,a.attname,a.atttypid," +
+		"a.attnum,a.attnotnull,a.attlen,a.atttypmod,d.adsrc " +
+		"from (pg_class c inner join pg_attribute a " +
+		"on (c.oid=a.attrelid) ) " +
+		"left outer join pg_attrdef d " +
+		"on (c.oid=d.adrelid and d.adnum=a.attnum) " +
+		"where " +
+		"c.relname like '"+tableNamePattern.toLowerCase()+"' and " +
+		"a.attname like '"+columnNamePattern.toLowerCase()+"' and " +
+		"a.attnum>0 " +
+		"order by c.relname,a.attnum";
+
+    r = connection.ExecSQL(query);
 
-	sql.append(
-		"                and a.attnum > 0" +
-		"            )" +
-		"        ) inner join pg_type t on" +
-		"            (" +
-		"                t.oid = a.atttypid" +
-		"            )" +
-		"    )" +
-		"    left outer join pg_attrdef d on" +
-		"        (" +
-		"            c.oid = d.adrelid" +
-		"            and a.attnum = d.adnum" +
-		"        )" +
-		"    left outer join pg_description e on" +
-		"        (" +
-		"            e.objoid = a.attrelid");
-
-	if (connection.haveMinimumServerVersion("7.2")) {
-		sql.append(
-			"            and e.objsubid = a.attnum" +
-			"            and e.classoid = (select oid from pg_class where relname = \'pg_class\')");
-	}
+    while(r.next()) {
+	byte[][] tuple = new byte[18][0];
 
-	sql.append(
-		"        ) " +
-		"order by" +
-		"    c.relname, a.attnum");
-
-	java.sql.ResultSet r = connection.ExecSQL(sql.toString());
-	while (r.next()) {
-		byte[][] tuple = new byte[18][0];
-
-		String nullFlag = r.getString(6);
-		String typname = r.getString(10);
-
-		tuple[0] = "".getBytes();				// Catalog name
-		tuple[1] = "".getBytes();				// Schema name
-		tuple[2] = r.getBytes(2);				// Table name
-		tuple[3] = r.getBytes(3);				// Column name
-		tuple[4] = Integer.toString(connection.getSQLType(typname)).getBytes();	// Data type
-		tuple[5] = typname.getBytes();			// Type name
-
-		// Column size
-		// Looking at the psql source,
-		// I think the length of a varchar as specified when the table was created
-		// should be extracted from atttypmod which contains this length + sizeof(int32)
-		if (typname.equals("bpchar") || typname.equals("varchar")) {
-			int atttypmod = r.getInt(8);
-			tuple[6] = Integer.toString(atttypmod != -1 ? atttypmod - VARHDRSZ : 0).getBytes();
-		} else {
-			tuple[6] = r.getBytes(7);
-		}
-
-		tuple[7] = null;						// Buffer length
-		tuple[8] = "0".getBytes();				// Decimal Digits - how to get this?
-		tuple[9] = "10".getBytes();				// Num Prec Radix - assume decimal
-		tuple[10] = Integer.toString(nullFlag.equals("f") ?
-			java.sql.DatabaseMetaData.columnNullable :
-			java.sql.DatabaseMetaData.columnNoNulls).getBytes();	// Nullable
-		tuple[11] = r.getBytes(11); 			// Description (if any)
-		tuple[12] = r.getBytes(9);				// Column default
-		tuple[13] = null;						// sql data type (unused)
-		tuple[14] = null;						// sql datetime sub (unused)
-		tuple[15] = tuple[6];					// char octet length
-		tuple[16] = r.getBytes(5);				// ordinal position
-		tuple[17] = (nullFlag.equals("f") ? "YES" : "NO").getBytes();	// Is nullable
-
-		v.addElement(tuple);
-	}
-	r.close();
+	// Fetch the description for the table (if any)
+	String getDescriptionStatement =
+		connection.haveMinimumServerVersion("7.2") ?
+		"select col_description(" + r.getInt(1) + "," + r.getInt(5) + ")" :
+	    "select description from pg_description where objoid=" + r.getInt(1);
+
+	java.sql.ResultSet dr = connection.ExecSQL(getDescriptionStatement);
 
+	if(((org.postgresql.ResultSet)dr).getTupleCount()==1) {
+	  dr.next();
+	  tuple[11] = dr.getBytes(1);
+	} else
+		tuple[11] = null;
+	dr.close();
+
+	tuple[0] = "".getBytes();	// Catalog name
+	tuple[1] = "".getBytes();	// Schema name
+	tuple[2] = r.getBytes(2);	// Table name
+	tuple[3] = r.getBytes(3);	// Column name
+
+	dr = connection.ExecSQL("select typname from pg_type where oid = "+r.getString(4));
+	dr.next();
+	String typname=dr.getString(1);
+	dr.close();
+        tuple[4] = Integer.toString(connection.getSQLType(typname)).getBytes();	// Data type
+	tuple[5] = typname.getBytes();	// Type name
+
+	// Column size
+	// Looking at the psql source,
+	// I think the length of a varchar as specified when the table was created
+	// should be extracted from atttypmod which contains this length + sizeof(int32)
+	if (typname.equals("bpchar") || typname.equals("varchar")) {
+	  int atttypmod = r.getInt(8);
+	  tuple[6] = Integer.toString(atttypmod != -1 ? atttypmod - VARHDRSZ : 0).getBytes();
+	} else
+	  tuple[6] = r.getBytes(7);
+
+	tuple[7] = null;	// Buffer length
+
+	tuple[8] = "0".getBytes();	// Decimal Digits - how to get this?
+	tuple[9] = "10".getBytes();	// Num Prec Radix - assume decimal
+
+	// tuple[10] is below
+	// tuple[11] is above
+
+	tuple[12] = r.getBytes(9);	// column default
+
+	tuple[13] = null;	// sql data type (unused)
+	tuple[14] = null;	// sql datetime sub (unused)
+
+	tuple[15] = tuple[6];	// char octet length
+
+	tuple[16] = r.getBytes(5);	// ordinal position
+
+	String nullFlag = r.getString(6);
+	tuple[10] = Integer.toString(nullFlag.equals("f")?java.sql.DatabaseMetaData.columnNullable:java.sql.DatabaseMetaData.columnNoNulls).getBytes();	// Nullable
+	tuple[17] = (nullFlag.equals("f")?"YES":"NO").getBytes();	// is nullable
+
+	v.addElement(tuple);
+      }
+    r.close();
     return new ResultSet(connection, f, v, "OK", 1);
   }